Spark Plugs.. Longer tip vs Standard tip..?? - JeepForum.com
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post #1 of 44 Old 10-20-2015, 09:21 AM Thread Starter
JOHNWON454
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Spark Plugs.. Longer tip vs Standard tip..??

I been researching this subject and can't seem to nail down which is currently preferred..
For example; NGK FR5-1 vs NGK ZFR5F-11

Or; Champion RC12YC vs Champion RC12LC4

I already understand the advantages of going to a lower heat range as for aiding in the prevention of pre-ignition.. So I don't really want to throw that in the mix at this point..

I'm trying to decide if this new longer tip is preferred over the OEM standard tip like used in the 93-97 5.2 engines.

Thanks to anyone who can shed some light on the matter based on experience.

PS:
I have seen some links that keep getting referred to when this topic comes up in other forums.. So if you choose to refer one that you believe to that will add clarity on this subject, feel free.. It may be one I have not seen yet...
Also, this plug selection will be used in this case on a stock OEM ignition system. This vehicle likely needs a plenum gasket and therefore drinks it's share of oil.

Sincerely: John

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post #2 of 44 Old 10-20-2015, 09:24 AM
XJ93
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I always use what the manufacturer has on the emissions tag. In the case of early V8 ZJ I use the RC12YC Copper Core Champions. There is no need for a "longer tip" or platinum or +4 type plug.
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post #3 of 44 Old 10-20-2015, 09:37 AM Thread Starter
JOHNWON454
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Originally Posted by XJ93 View Post
I always use what the manufacturer has on the emissions tag. In the case of early V8 ZJ I use the RC12YC Copper Core Champions. There is no need for a "longer tip" or platinum or +4 type plug.
I do realize what you are saying, but if I understand correctly, the manufacture changed this in 1998 to the longer tip Champions while keeping the heat range the same.
I've read where at least one post by someone who seems confident in what he posts... Quote; "Why in God's green Earth would you want to digress back to the old style spark plugs??!? The newer style RC12LC4 improves the performance of the Magnum engines! They idle smoother, and seem to have a little more "crispness" to the throttle response.
I upgrade all the Magnum engines to the newer style plug and gap, and have noticed improvements almost every single time.

They changed the plug design for better flame propagation, and that in turn helped with emissions as well as adding a touch of power.

Stick with the OEM Champion plugs. There's nothing to gain by running a different brand, and lots of times the non-OEM brands can cause a Chrysler product to run worse than it did in the first place!"
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post #4 of 44 Old 10-20-2015, 09:42 AM
XJ93
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While they seem confident, I hold everything in reserve unless I see numbers. Seat of the pants dyno holds no sway with me. I have run different plugs in many different engines and I can tell you that I have always had the best results with what the manufacturer designed the ignition system to work with. If it's all stock, stay with what the tag calls for. You put an MSD coil or something of that ilk into it, then you improve plugs and wires as well. It's kind of like throwing a cold air intake on it and not doing anything to the exhaust system to accommodate and make use of the increased air.
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post #5 of 44 Old 10-20-2015, 09:52 AM Thread Starter
JOHNWON454
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Originally Posted by XJ93 View Post
While they seem confident, I hold everything in reserve unless I see numbers. Seat of the pants dyno holds no sway with me. I have run different plugs in many different engines and I can tell you that I have always had the best results with what the manufacturer designed the ignition system to work with. If it's all stock, stay with what the tag calls for. You put an MSD coil or something of that ilk into it, then you improve plugs and wires as well. It's kind of like throwing a cold air intake on it and not doing anything to the exhaust system to accommodate and make use of the increased air.
That is a fair assessment of his post...
I'm still wondering if Chrysler made this change for a good reason..??
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post #6 of 44 Old 10-20-2015, 10:04 AM
XJ93
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From what I can gather from calling my buddy at a Chrysler dealer is that the plugs were changed to help reduce emissions numbers. It didn't help a whole lot, but enough for them to meet the requirement at the time. It was all across the board and, if you pay attention, follows right along with when they eliminated the egr valve.
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post #7 of 44 Old 10-20-2015, 10:11 AM Thread Starter
JOHNWON454
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Originally Posted by XJ93 View Post
From what I can gather from calling my buddy at a Chrysler dealer is that the plugs were changed to help reduce emissions numbers. It didn't help a whole lot, but enough for them to meet the requirement at the time. It was all across the board and, if you pay attention, follows right along with when they eliminated the egr valve.
Interesting....
Is this new plug what they would likely install today if one would take in a pre 1998 5.2 vehicle in for plug change at the dealer?
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post #8 of 44 Old 10-20-2015, 12:16 PM
XJ93
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No because the spec for emissions standards for previous models would be RC12YC, that is what they would put in. Now I know some people would argue that "spec for previous models" would equate to still using ATF3 instead of +4 but that's a different beast. We know for a fact that the transmissions work as designed when the proper +4 fluid is used no matter what the manual says. The engine computer was programmed to utilize the ignition system as it was designed. OBD2 may have the capability to learn to a degree but unless you actually go in and change parameters it will always try to run as programmed. This is the reason I never swap out an O2 sensor because I have an O2 code. All that means is you are beyond parameters set by the manufacturer. There is no reason to stray from what the manufacturer has designed it to work.
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post #9 of 44 Old 10-20-2015, 01:33 PM
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Interesting. The 4.0 went the other way. The ZJs us an RC12LYC which has the projected tip and the WJs use the RC12EEC which has a non-projected tip.

I've use non-projected tip plugs in my 93 and didn't notice a gain or loss of power or economy. I was trying other plugs and most other plug brands don't make that plug with the projected tip. I've gone back to the stock Champions since it didn't seems to matter and cheap is a quality overcoming many faults.
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post #10 of 44 Old 10-20-2015, 01:34 PM Thread Starter
JOHNWON454
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That make sense..
It would be interesting for someone to do some extensive comparison to see if it may actually be an improvement all the way around.

Thanks for your time and insight.
Sincerely: John
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post #11 of 44 Old 10-20-2015, 02:28 PM
JonS
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I also use the non-projected tip Champions and car runs great! I prefer to have the plug tips further away from the pistons!


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post #12 of 44 Old 10-20-2015, 02:44 PM Thread Starter
JOHNWON454
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Originally Posted by JonS View Post
I also use the non-projected tip Champions and car runs great! I prefer to have the plug tips further away from the pistons!
Thanks for the feedback.
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post #13 of 44 Old 10-20-2015, 02:57 PM
zjosh93
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Quote:
Originally Posted by JonS View Post
I also use the non-projected tip Champions and car runs great! I prefer to have the plug tips further away from the pistons!
If your piston is out of place enough to hit the plug very bad things are happening and what type of plug you are running is the least of your concerns.

IMHO projected tip plugs are a crutch for poor combustion chamber design but it doesn't seem to matter much. I'd bet you couldn't see the difference even on a dyno.
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post #14 of 44 Old 10-20-2015, 03:25 PM
JonS
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Quote:
Originally Posted by zjosh93 View Post
If your piston is out of place enough to hit the plug very bad things are happening and what type of plug you are running is the least of your concerns.

IMHO projected tip plugs are a crutch for poor combustion chamber design but it doesn't seem to matter much. I'd bet you couldn't see the difference even on a dyno.
Agreed. I don't think extending the tip of the plug several mm's makes one bit of difference to emissions, gas mileage, or power. The fuel is compressed by the piston and the firing of the plug produces the power be it flush, 5 mm extended or just short of the piston top.
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post #15 of 44 Old 10-21-2015, 06:46 AM Thread Starter
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I ran across this of interest...

Kenne Bell company says they did extensive research and testing on their in-house DynoJet 148C, and recommend the "V" design NGK ZFR5F11 (stock number 2262, resistor inside 4,000 ohms) for non-supercharged, and ZFR6F11 (one heat range cooler) for blown 5.2/5.9 Dodges.

These V design NGK sparkplugs have a v-notch cut into the center electrode that increases the sharp edges and moves the spark away from the center. Sharp edges reduce the voltage need for the spark to start. The nose of these plugs seem to be slightly more projected than the Champion RC12YC. The ZFR5F11 is also NGK's recommended Viper Aluminum V-10 plug.

The projected-nose configuration moves the spark gap a bit farther into the combustion chamber, which tends to improve efficiency by shortening the distance traveled by the flame front and also making the combustion process more regular. But there is a more important benefit: the projected-nose plug provides, in many engines, what effectively is a broader heat range than you get with the conventional flush-nose type. The projected nose is more directly exposed to the fire in the combustion chamber, and quickly comes up to a temperature high enough to burn away fouling deposits after ignition occurs. Then during the subsequent intake phase this plug's exposed tip is cooled by the swirling air/fuel mixture. In this fashion the higher temperatures existing at full-throttle operating conditions are to some extent compensated by the greater volume of cooling air, and the net effect is to make the projected-nose plug better able to cope with the conflicting demands of traffic and highway travel.

These ZFR5F11 plugs were reported to noticeably pep up the 5.9 V8 engine over Champion's plug.

NGK's standard recommended sparkplug for the 3.9/5.2/5.9 Magnum engines is the FR4 (stock number 5155) or FR5-1, (stock number 7252).
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